Hypertension is the most important potentially reversible risk factor for cerebrovascular disease in all age groups. A continuous relation exists between increasing blood pressure and the likelihood of stroke, such that a 7 mm Hg increment in diastolic blood pressure is associated with a doubling of the relative risk of stroke.1 The preventive role of antihypertensive treatment in reducing morbidity and mortality from stroke is well established: treatment that produces a long term reduction in diastolic blood pressure of 5-6 mm Hg results in a 35-40% fall in the risk of stroke.^2,3

About four fifths of patients with stroke have raised blood pressure on admission to hospital and about one third have a history of hypertension.4 Raised blood pressure usually falls spontaneously within a few days5; 10 days after an ischaemic stroke two thirds of patients are normotensive.6 Doctors are therefore faced with the problem of deciding in whom and when to treat raised blood pressure.

There is conflicting evidence about the prognostic significance of hypertension immediately after acute stroke. Using multivariate analysis, Carlberg and colleagues found that previous hypertension most strongly predicted raised initial blood pressure in patients admitted to an acute stroke unit.7 Hypertension preceding stroke is, however, not invariably associated with an adverse prognosis in terms of either early fatality or functional recovery.*RF 8-10* Although early studies suggested that …